Communication system, communication method, and storage

ABSTRACT

A communication system is a communication system provided in a mobile body and including an acquirer configured to acquire a destination of the mobile body, and a communicator configured to communicate with a communication device outside the mobile body using an antenna, in which the communicator is configured to increase directivity of the antenna in a direction from a position of the mobile body to the destination when the destination is acquired by the acquirer.

CROSS-REFERENCE TO RELATED APPLICATION

Priority is claimed on Japanese Patent Application No. 2018-203210,filed Oct. 29, 2018, the content of which is incorporated herein byreference.

BACKGROUND Field of the Invention

The present invention relates to a communication system, a communicationmethod, and a storage medium.

Description of Related Art

In the related art, a technology for changing the directivity of anantenna according to a traveling angle of a vehicle or a position of thevehicle relative to a position of a base station outside the vehicle ininformation communication in which radio waves are transmitted andreceived between devices mounted in the vehicle and the base station orthe like is known (for example, Japanese Unexamined Patent Application,First Publication No. 2005-142658).

SUMMARY

Incidentally, in recent years, research on information communicationusing a fifth generation (5G) communication system in a device mountedin a vehicle has been performed. The device mounted in the vehicle maycommunicate with other devices, in addition to a base station in thefifth generation communication system. However, in the related art,although communication quality can be improved by controlling an antennaon the basis of a relationship between the vehicle and the base station,it may be difficult to improve communication quality between the vehicleand other devices.

An aspect of the present invention has been made in view of suchcircumstances, and an object of the present invention is to provide acommunication system, a communication method, and a storage medium thatcan improve communication quality between a vehicle and another device.

The communication system, the communication method, and the storagemedium according to the present invention adopt the followingconfigurations.

(1) A communication system according to an aspect of the presentinvention is a communication system provided in a mobile body andincluding an acquirer configured to acquire a destination of the mobilebody, and a communicator configured to communicate with a communicationdevice outside the mobile body using an antenna, wherein thecommunicator is configured to increase directivity of the antenna in adirection from a position of the mobile body to the destination when thedestination is acquired by the acquirer.

(2) In the above aspect (1), the communicator is configured to increasethe directivity of the antenna in a direction from a position afterchange to the destination when the position of the mobile body changes.

(3) In the above aspects (1), the communicator is configured to increasereception sensitivity of the antenna when the destination is notacquired by the acquirer.

(4) In the above aspects (1), the acquirer is further configured toacquire the position of the mobile body, and the communicator isconfigured to decrease the directivity of the antenna or sets theantenna to nondirectional when the distance between the position of themobile body and the destination is within a predetermined distance.

(5) In the above aspects (3), the communicator is configured to increasethe reception sensitivity of the antenna as the position of the mobilebody approaches the destination.

(6) A communication method according to an aspect of the inventionincludes acquiring, by a computer provided in a mobile body, adestination of the mobile body; communicating, by the computer providedin the mobile body, with a communication device outside the mobile bodyusing an antenna; and increasing, by the computer provided in the mobilebody, directivity of the antenna in a direction from a position of themobile body to the destination when the destination is acquired.

(7) A storage medium according to an aspect of the invention is astorage medium storing a program causing a computer provided in a mobilebody to: acquire a destination of the mobile body; communicate with acommunication device outside the mobile body using an antenna; andincrease directivity of the antenna in a direction from a position ofthe mobile body to the destination when the destination is acquired.

According to the above aspects (1) to (7), it is possible to improvecommunication quality between the vehicle and another device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of a configuration of acommunication system 1 according to an embodiment.

FIG. 2 is a diagram conceptually showing a process of a sensitivityadjuster 115.

FIG. 3 is a diagram conceptually showing a process of a directivityadjuster 116.

FIG. 4 is a diagram conceptually showing another process of thesensitivity adjuster 115.

FIG. 5 is a flowchart showing an example of a series of flows related toa reception process of the sensitivity adjuster 115.

FIG. 6 is a flowchart showing an example of a series of flows related toa transmission process of the sensitivity adjuster 115.

FIG. 7 is a flowchart showing an example of a series of flows related tothe process of the directivity adjuster 116.

DESCRIPTION OF EMBODIMENTS

Hereinafter, an embodiment of a communication system, a communicationmethod, and a storage medium of the present invention will be describedwith reference to the drawings.

Embodiment

FIG. 1 is a diagram showing an example of a configuration of acommunication system 1 according to the embodiment. The communicationsystem 1 is a device that is mounted in a vehicle and performscommunication between other devices mounted in the vehicle (hereinafter,in-vehicle devices) and devices outside the vehicle (hereinafter,external devices). The vehicle in which the communication system 1 ismounted (hereinafter, the host vehicle M) is, for example, a vehiclesuch as a two-wheeled vehicle, a three-wheeled vehicle, or afour-wheeled vehicle. The communication system 1 includes a navigationdevice 10, an antenna 20, and a communication device 100.

[Navigation Device 10]

The navigation device 10 includes, for example, a global navigationsatellite system (GNSS) receiver 11, a navigation human machineinterface (HMI) 12, and a route determiner 13. The navigation device 10holds first map information 14 in a storage device such as a hard diskdrive (HDD) or a flash memory. The GNSS receiver 11 specifies a positionof the host vehicle M on the basis of a signal received from a GNSSsatellite. The navigation HMI 12 includes a display device, a speaker, atouch panel, keys, and the like. The route determiner 13, for example,determines a route (hereinafter, an on-map route) from the position ofthe host vehicle M (or any input position) specified by the GNSSreceiver 11 to a destination input by the occupant using the navigationHMI 12 by referring to the first map information 14. The first mapinformation 14 is, for example, information in which a road shape isrepresented by links indicating roads and nodes connected by the links.The navigation device 10 may perform route guidance using the navigationHMI 12 on the basis of the on-map route. The navigation device 10 may berealized, for example, by a function of a terminal device such as asmartphone or a tablet terminal possessed by the occupant. Thenavigation device 10 may transmit a current position and a destinationto a navigation server via the communication device 100 and acquire thesame route as the on-map route from the navigation server.

[Antenna 20]

The antenna 20 includes an oscillator, an overemphasis circuit, anamplifier, and the like, and transmits or receives radio waves. Areception sensitivity and directivity of the antenna 20 are controlledby the communication device 100. The antenna 20 is, for example, amassive multiple input and multiple output (MIMO) antenna, and has afunction of performing communication according to a communication schemeusing a fifth generation (5G) communication system.

[Communication Device 100]

The communication device 100 communicates with an external device usinga cellular network, a Wi-Fi network, Bluetooth (registered trademark),dedicated short range communication (DSRC), or the like or communicateswith various server devices via a wireless base station. Hereinafter, acase in which the communication device 100 performs communication usinga cellular network using a fifth generation communication system will bedescribed. The communication device 100 includes a controller 110. Thecontroller 110, for example, includes a destination acquirer 111, aposition acquirer 112, a reception processor 113, a transmissionprocessor 114, a sensitivity adjuster 115, and a directivity adjuster116 by a hardware processor such as a central processing unit (CPU)executing a program (software) stored in a storage (not shown).

The destination acquirer 111 acquires information indicating adestination acquired by the navigation device 10. The position acquirer112 acquires information indicating a current position of the hostvehicle M acquired by the GNSS receiver 11.

The reception processor 113 performs a process related to communication(that is, reception) from the external device to the in-vehicle device.The reception processor 113, for example, outputs information acquiredby demodulating and combining the radio waves received by the antenna 20to the in-vehicle device that is a reception target.

The transmission processor 114 performs a process related tocommunication (that is, transmission) from the in-vehicle device to theexternal device. For example, the transmission processor 114 encodes andmodulates information transmitted from the in-vehicle device to theexternal device, and causes the antenna 20 to transmit the resultantinformation.

The sensitivity adjuster 115 adjusts the reception sensitivity andtransmission sensitivity of the antenna 20 on the basis of thedestination of the host vehicle M. Details of a process of thesensitivity adjuster 115 will be described below. The directivityadjuster 116 adjusts the directivity of the antenna 20 on the basis ofthe destination of the host vehicle M. Details of the process of thedirectivity adjuster 116 will be described below.

[Communication Using Fifth Generation Communication System]

The communication using the fifth generation communication system willbe described prior to description of processes of the sensitivityadjuster 115 and the directivity adjuster 116. In recent years, researchon Vehicle to Everything (V2X) that enables the host vehicle M (thein-vehicle device) and various things to communicate with each other byusing a fifth generation communication system has proceeded. Examples ofV2X include vehicle-to-vehicle communication (hereinafter referred to asV2V communication (Vehicle to Vehicle)), vehicle-to-infrastructurecommunication (hereinafter referred to as V2I communication (Vehicle toInfrastructure)), vehicle-to-network communication (hereinafter referredto as V2N communication (Vehicle to Network)), and vehicle-to-pedestriancommunication (hereinafter referred to as V2P communication (Vehicle toPedestrian)).

In this case, the external device is, for example, a terminal devicesuch as a smartphone possessed by a pedestrian, a portable personalcomputer such as a tablet computer (a tablet PC) possessed by thepedestrian, or a navigation device included in another vehicle. Thein-vehicle device is, for example, a terminal device such as asmartphone or a tablet terminal held by an occupant of the host vehicleM, or the navigation device 10. Hereinafter, a case in which thein-vehicle device is the navigation device 10 will be described.

For example, when there is a popular spot other than the destinationaround the destination, the occupant of the host vehicle M may want tostop at the spot. In this case, it is preferable for the in-vehicledevice to present the presence of the popular spot to the occupant ofthe host vehicle M on the basis of information received from apedestrian or vehicle present at the popular spot around the destinationthrough V2V communication or V2P communication.

When the destination of the host vehicle M is not particularlydetermined, it is preferable for the communication system 1 to transmitinformation on the current position of the host vehicle M as informationthat an external device of the nearby pedestrian or vehicle uses forestimation of a mixed state (in other words, the presence of the popularspot) to the nearby pedestrian or vehicle through V2V communication orV2P communication.

Hereinafter, the processes of the sensitivity adjuster 115 and thedirectivity adjuster 116 when the communication system 1 receives theinformation from the pedestrian or vehicle around the popular spot willfirst be described, and then, the processes of the sensitivity adjuster115 and the directivity adjuster 116 when the communication system 1transmits the information on the current position of the host vehicle Mto another person present around the host vehicle M will be described.

[Reception Process when Host Vehicle is Distant from Destination]

Hereinafter, processes of the sensitivity adjuster 115 and thedirectivity adjuster 116 when the destination of the host vehicle M isdetermined and the host vehicle M is present at a place distant from thedestination will be described. FIG. 2 is a diagram conceptually showingthe process of the sensitivity adjuster 115. In FIG. 2, a destination DNis determined for the host vehicle M according to an operation of thenavigation device 10 by the occupant. Hereinafter, a case in which thereare popular spots SPT1 to SPT3 around the destination DN will bedescribed.

The sensitivity adjuster 115 adjusts the reception sensitivity of theantenna 20 on the basis of information indicating the destination DNacquired by the destination acquirer 111 and information indicating thecurrent position of the host vehicle M acquired by the position acquirer112. For example, when a distance from the current position of the hostvehicle M to the destination DN exceeds a predetermined distance Dt(that is, when the destination DN is distant from the current position),the sensitivity adjuster 115 increases the reception sensitivity of theantenna 20 when the current position of the host vehicle M becomescloser to the destination DN. In FIG. 2, the sensitivity adjuster 115calculates a distance D0 from the destination DN to the host vehicle Mon the basis of the current position acquired at a certain time (t0) andthe destination DN, for example. The sensitivity adjuster 115 calculatesa distance D1 from the destination DN to the host vehicle M on the basisof the current position acquired at a time (t1) after a predeterminedtime has elapsed from the certain time (t0) and the destination DN. Thesensitivity adjuster 115 increases the reception sensitivity of theantenna 20 since the distance D1 out of the distance D0 and the distanceD1 is a shorter distance (that is, the host vehicle M is approaching thedestination DN).

The directivity adjuster 116 adjusts the directivity of the antenna 20on the basis of the information indicating the destination DN acquiredby the destination acquirer 111 and the information indicating thecurrent position of the host vehicle M acquired by the position acquirer112. For example, when the distance from the current position of thehost vehicle M to the destination DN exceeds the predetermined distanceDt (that is, when the destination DN is distant from the currentposition), the directivity adjuster 116 increases the directivity of theantenna 20 in the destination direction as the current position of thehost vehicle M approaches the destination DN. In FIG. 2, the directivityadjuster 116 calculates a distance D0 from the destination DN to thehost vehicle M on the basis of the current position acquired at acertain time (t0) and the destination DN, for example. The directivityadjuster 116 calculates the distance D1 from the destination DN to thehost vehicle M on the basis of the current position acquired at the time(t1) and the destination DN. The directivity adjuster 116 increases thedirectivity of the antenna 20 in the destination direction since thedistance D1 out of the distance D0 and the distance D1 is a shorterdistance (that is, the host vehicle M is approaching the destinationDN). Since a positional relationship between the current position andthe destination DN changes according to traveling of the host vehicle M,the directivity adjuster 116 acquires the current position and thedestination DN to specify (update) the destination direction always orat predetermined time intervals, and uses the destination direction tocontrol the directivity of the antenna 20.

The sensitivity adjuster 115, for example, may adjust the receptionsensitivity in a stepwise manner to increase the reception sensitivityat a timing when it has been determined that the host vehicle M isapproaching the destination DN at the time (t1). The sensitivityadjuster 115 may increase the reception sensitivity linearly until apredetermined time elapses from the timing (that is, until a next timingwhen the distance from the destination DN to the host vehicle M iscalculated). The directivity adjuster 116, for example, may adjust thedirectivity in a stepwise manner to increase the directivity at a timingwhen it has been determined that the host vehicle M is approaching thedestination DN at the time (t1). The directivity adjuster 116 mayincrease the directivity linearly until a predetermined time elapsesfrom the timing.

Accordingly, the sensitivity adjuster 115 can make it easier to receiveinformation from an external device around the destination DN as thehost vehicle M approaches the destination DN. For example, thesensitivity adjuster 115 can make it easier to receive information froman external device present at a spot SPT (a shown spot SPT1) even whenthe spot SPT is present at an end portion of a range in whichinformation can be received by the antenna 20. The directivity adjuster116 can make it easier to receive information from an external devicepresent at a position closer to the destination DN as the host vehicle Mapproaches the destination DN. For example, even when a certain spot SPTis present around the destination DN, the directivity adjuster 116 canmake it difficult for information from the spot SPT to be received (orprevent the information from being received) in a case in which the hostvehicle M needs to move in a direction away from the destination DN inorder to go to the spot SPT (for example, the shown spot SPT2).

The sensitivity adjuster 115 may be configured to immediately increasethe directivity of the antenna 20 in a direction of the destination DNwhen the information indicating the destination DN is acquired by thedestination acquirer 111.

[Process of Each Functional Unit]

The sensitivity adjuster 115 and the directivity adjuster 116 may notsimultaneously change the sensitivity and the directivity to performprocesses. For example, when the sensitivity adjuster 115 increases thereception sensitivity of the antenna 20 as the host vehicle M approachesthe destination DN, the directivity adjuster 116 may not increase thedirectivity of the antenna 20. In this case, the communication device100 may not include the directivity adjuster 116. For example, when thedirectivity adjuster 116 increases the directivity of the antenna 20 inthe direction of the destination DN as the host vehicle M approaches thedestination DN, the sensitivity adjuster 115 may not increase thereception sensitivity of the antenna 20. In this case, the communicationdevice 100 may not include the sensitivity adjuster 115.

[Reception Process when Host Vehicle is Close to Destination]

Hereinafter, a process of the directivity adjuster 116 when the hostvehicle M is present at a place close to the destination will bedescribed. FIG. 3 is a diagram conceptually showing the process of thedirectivity adjuster 116. The directivity adjuster 116 adjusts thedirectivity of the antenna 20 on the basis of the information indicatingthe destination DN acquired by the destination acquirer 111 and theinformation indicating the current position of the host vehicle Macquired by the position acquirer 112. The directivity adjuster 116, forexample, decreases the directivity of the antenna 20 when the distancebetween the current position of the host vehicle M and the destinationDN (the shown distance D2) is within the predetermined distance Dt (thatis, when the destination DN is close to the current position). Settingthe antenna 20 to be nondirectional is included in decreasing thedirectivity of the antenna 20.

Accordingly, the directivity adjuster 116 can make it easier to receiveinformation from an external device present around the destination DN(at the shown spots SPT2 to SPT3) when the host vehicle M is present ata position close to the destination DN.

For example, when the distance D2 is within the predetermined distanceDt (that is, when the destination DN is close to the current position),the sensitivity adjuster 115 may increase the reception sensitivity ofthe antenna 20 (for example, to a maximum). The sensitivity adjuster 115may control the reception sensitivity of the antenna 20 so that thereception sensitivity of the antenna 20 is maximized before the distanceD2 matches the predetermined distance Dt. Here, a relationship between alevel of a predetermined reception sensitivity (hereinafter referred toas a predetermined reception sensitivity X1) controlled by thesensitivity adjuster 115 when the distance D2 is within thepredetermined distance Dt and a level of a predetermined receptionsensitivity (hereinafter referred to as a predetermined receptionsensitivity X2) controlled by the sensitivity adjuster 115 when thedistance D2 exceeds the predetermined distance Dt is predeterminedreception sensitivity X1>predetermined reception sensitivity X2. Whenthe distance D2 is within the predetermined distance Dt, the sensitivityadjuster 115 may immediately control the predetermined receptionsensitivity X2 such that the reception sensitivity becomes thepredetermined reception sensitivity X1, and may gradually control thepredetermined reception sensitivity X2 such that the receptionsensitivity becomes the reception sensitivity X1 after the distance D2becomes within the predetermined distance Dt. The sensitivity adjuster115 may increase the reception sensitivity as the host vehicle Mapproaches the destination DN from the current position.

The sensitivity adjuster 115 may increase the reception sensitivity asthe host vehicle M approaches the destination DN when the distance D2exceeds the predetermined distance Dt. In this case, when the distanceD2 exceeds the predetermined distance Dt, the sensitivity adjuster 115may not further increase the reception sensitivity in a case in whichthe reception sensitivity becomes the predetermined receptionsensitivity X1. In this case, the predetermined reception sensitivity X1is a maximum reception sensitivity when the distance D2 exceeds thepredetermined distance Dt.

[Transmission Process when Destination is Determined: SensitivityAdjuster 115]

Hereinafter, a process of the sensitivity adjuster 115 when thedestination of the host vehicle M is determined will be described. FIG.4 is a diagram conceptually showing another process of the sensitivityadjuster 115.

The sensitivity adjuster 115 adjusts an output when information istransmitted using the antenna 20 (hereinafter referred to as atransmission output) on the basis of the information indicating thedestination DN acquired by the destination acquirer 111 and theinformation indicating the current position of the host vehicle Macquired by the position acquirer 112. The sensitivity adjuster 115, forexample, increases the transmission output of the antenna 20 as thecurrent position of the host vehicle M approaches the destination DN. InFIG. 4, the sensitivity adjuster 115 calculates a distance D0 from thedestination DN to the host vehicle M on the basis of the currentposition acquired at a certain time (t0) and the destination DN, forexample. The sensitivity adjuster 115 calculates the distance D1 fromthe destination DN to the host vehicle M on the basis of the currentposition acquired at the time (t1) and the destination DN. Thesensitivity adjuster 115 increases the transmission output since thedistance D1 out of the distance D0 and the distance D1 is a shorterdistance (that is, the host vehicle M approaches the destination DN).

The sensitivity adjuster 115, for example, may adjust the transmissionoutput in a stepwise manner to increase the transmission output at atiming when it has been determined that the host vehicle M isapproaching the destination DN at the time (t1). The sensitivityadjuster 115 may increase the transmission output linearly until apredetermined time elapses from the timing (that is, until a next timingwhen the distance from the destination DN to the host vehicle M iscalculated).

Accordingly, the sensitivity adjuster 115 can make it easy forinformation to be received by an external device around the destinationDN as the host vehicle M approaches the destination DN. For example, thesensitivity adjuster 115 can make it easier for information to bereceived by an external device present at a spot SPT (a shown spot SPT1)even when the spot SPT is present at an end portion of a range in whichinformation can be transmitted by the antenna 20. Accordingly, when thesensitivity adjuster 115 transmits a request for information onsurroundings of the external device to the external device, thesensitivity adjuster 115 makes it easy for the in-vehicle device toobtain the information.

[Transmission Process when Destination is not Determined: SensitivityAdjuster 115]

When the destination DN of the host vehicle M is not determined, thesensitivity adjuster 115 may not change the transmission output of theantenna 20 according to the current position of the host vehicle M. Forexample, when the information indicating the destination DN of the hostvehicle M has not been acquired by the destination acquirer 111, thesensitivity adjuster 115 keeps the transmission output of the antenna 20high (for example, at a maximum). Accordingly, the sensitivity adjuster115 makes it easier for the information on the current position of thehost vehicle M to be used as the information that the external device ofthe nearby pedestrian or vehicle uses for estimation of the mixed state(in other words, the presence of a popular spot).

[Transmission Process when Destination is not Determined: DirectivityAdjuster 116]

When the destination DN of the host vehicle M is not determined, thedirectivity adjuster 116 may not change the directivity of the antenna20 according to the current position of the host vehicle M. For example,when the information indicating the destination DN of the host vehicle Mis not acquired by the destination acquirer 111, the directivityadjuster 116 keeps the directivity of the antenna 20 low. Accordingly,the directivity adjuster 116 makes it easier for the information on thecurrent position of the host vehicle M to be used as information thatthe external device of the nearby pedestrian or vehicle uses forestimation of the mixed state (in other words, the presence of a popularspot).

[Reception Process Flow of Sensitivity Adjuster 115]

FIG. 5 is a flowchart showing an example of a series of flows related tothe reception process of the sensitivity adjuster 115. First, thesensitivity adjuster 115 determines whether or not the informationindicating the destination of the host vehicle M has been acquired bythe destination acquirer 111 (step S100). When the destination of thehost vehicle M has been acquired, the sensitivity adjuster 115calculates the distance between the current position acquired by theposition acquirer 112 and the destination, and increases the receptionsensitivity of the antenna 20 as the host vehicle M (current position)approaches the destination (step S102). When the destination of the hostvehicle M has not been acquired, the sensitivity adjuster 115 ends theprocess without changing the reception sensitivity (step S104).

[Transmission Process Flow of Sensitivity Adjuster 115]

FIG. 6 is a flowchart showing an example of a series of flows related tothe transmission process of the sensitivity adjuster 115. First, thesensitivity adjuster 115 determines whether the information indicatingthe destination of the host vehicle M has been acquired by thedestination acquirer 111 (step S200). When the destination of the hostvehicle M has been acquired, the sensitivity adjuster 115 calculates thedistance between the current position acquired by the position acquirer112 and the destination, and increases the transmission output of theantenna 20 as the host vehicle M (current position) approaches thedestination (step S202). When the destination of the host vehicle M hasnot been acquired, the sensitivity adjuster 115 increases (for example,maximizes) the transmission output of the antenna 20 and ends theprocess (step S204).

[Process Flow of Directivity Adjuster 116]

FIG. 7 is a flowchart showing an example of a series of flows related toa process of the directivity adjuster 116. First, the directivityadjuster 116 determines whether or not the information indicating thedestination of the host vehicle M has been acquired by the GNSS receiver11 (step S300). When the destination of the host vehicle M has not beenacquired, the directivity adjuster 116 decreases the directivity of theantenna 20 and ends the process (step S302). When the destination of thehost vehicle M has been acquired, the directivity adjuster 116calculates the distance between the current position acquired by theposition acquirer 112 and the destination, and determines whether or notthe distance from the current position to the destination exceeds thepredetermined distance Dt (step S304). When the distance from thecurrent position to the destination exceeds the predetermined distanceDt (that is, the destination is distant from the current position), thedirectivity adjuster 116 calculates the distance between the currentposition acquired by the position acquirer 112 and the destination, andincreases the directivity of the antenna 20 in the destination directionas the host vehicle M (current position) approaches the destination(step S306). The directivity adjuster 116 decreases the directivity ofthe antenna 20 when the distance from the current position to thedestination is within the predetermined distance Dt (that is, thedestination is close to the current position) (step S308).

CONCLUSION OF EMBODIMENT

As described above, the communication system 1 according to theembodiment includes an acquirer (in this example, the destinationacquirer 111 and the position acquirer 112) that acquires a destinationof the mobile body (in this example, the host vehicle M) and theposition of the host vehicle M, and a communicator (in this example, thereception processor 113, the transmission processor 114, the sensitivityadjuster 115, and the directivity adjuster 116) that communicates with acommunication device (in this example, the external device) outside thehost vehicle M using the antenna 20, in which the sensitivity adjuster115 increases the reception sensitivity of the antenna 20 and increasesthe directivity of the antenna 20 in a direction of the destination as acurrent position of the host vehicle M acquired by the destinationacquirer 111 approaches a destination acquired by the position acquirer112, thereby improving communication quality between the host vehicle Mand the external device. Although a mode for carrying out the presentinvention has been described above using the embodiment, the presentinvention is not limited to the embodiment at all, and variousmodifications and substitutions may be made without departing from thespirit of the present invention.

What is claimed is:
 1. A communication system provided in a mobile bodyand including an acquirer configured to acquire a destination of themobile body, and a communicator configured to communicate with acommunication device outside the mobile body using an antenna, whereinthe communicator is configured to increase directivity of the antenna ina direction of the destination higher than a direction other than thedirection of the destination when the destination is acquired by theacquirer.
 2. The communication system according to claim 1, wherein thecommunicator is configured to increase the directivity of the antenna ina direction from a position after change to the destination when theposition of the mobile body changes.
 3. The communication systemaccording to claim 1, wherein the communicator is configured to increasereception sensitivity of the antenna when the destination is notacquired by the acquirer.
 4. The communication system according to claim1, wherein the acquirer is further configured to acquire the position ofthe mobile body, and the communicator is configured to decrease thedirectivity of the antenna or sets the antenna to nondirectional when adistance between the position of the mobile body and the destination iswithin a predetermined distance.
 5. The communication system accordingto claim 3, wherein the communicator is configured to increase thereception sensitivity of the antenna as the position of the mobile bodyapproaches the destination.
 6. A communication method comprising:acquiring, by a computer provided in a mobile body, a destination of themobile body; communicating, by the computer provided in the mobile body,with a communication device outside the mobile body using an antenna;and increasing, by the computer provided in the mobile body, directivityof the antenna in a direction of the destination higher than in adirection other than the direction of the destination when thedestination is acquired.
 7. A communication system provided in a mobilebody and including an acquirer configured to acquire a destination ofthe mobile body, and a communicator configured to communicate with acommunication device outside the mobile body using an antenna, whereinthe communicator is configured to increase directivity of the antenna ina direction from a position of the mobile body to the destination whenthe destination is acquired by the acquirer, wherein the acquirer isfurther configured to acquire the position of the mobile body, and thecommunicator is configured to decrease the directivity of the antenna orsets the antenna to nondirectional when a distance between the positionof the mobile body and the destination is within a predetermineddistance.
 8. The communication system according to claim 7, wherein thecommunicator is configured to increase reception sensitivity of theantenna as the position of the mobile body approaches the destination.